Liberals now point to the incompetence of Dutton's ragtag numbers men: Tony Pasin, Andrew Hastie, Zed Seselja and Michael Sukkar, all of whom are from the so-called "monkeypod" faction, named after the regular Tuesday lunchtime group that meets around a tropical timber table in the ministerial wing.

It was only on Thursday that Senator Cormann began seriously poring through the numbers himself that it hit: his mate Dutton had been relying on bad intel.

The Turnbull camp had been insistent all along that Dutton didn't have the numbers, even if the Prime Minister indicated his own doubts.

About 9:20pm on Thursday, 15 hours before the partyroom meeting, the ABC was told emphatically that Dutton did not have sufficient support.

And it was in this maelstrom of miscalculations by the challenger that Scott Morrison's candidacy emerged. He was the Turnbull candidate by virtue of not being Dutton, and having the best chance of cruelling the coup.

On Wednesday, efforts to bind Cormann to team Turnbull had been frantic.

A Turnbull consigliere had sought to conscript Cormann to the team.

And his WA colleague Linda Reynolds was seen having a robust conversation with him, arms rich with gesticulation, outside the Senate shortly before 11am. Her message? Unity.

But Cormann remained aloof.

"If only Mathias had called, we'd have shown him Dutton didn't have the numbers," one Turnbull backer said.

But at 4:30pm on Wednesday, just a few hours after declaring, "I support Malcolm Turnbull as Prime Minister", alongside the Prime Minister and the Treasurer at a media conference, Cormann advised Turnbull he had lost majority support of Liberals.

And it is unclear whether he had forensically checked this assessment before ventilating it to Turnbull.

He offered to resign as Finance Minister, but not before privately acknowledging Turnbull's assessment that his prime ministership was being attacked by "insurgents".

One Turnbull backer says if Cormann had stuck with the PM, Turnbull would've survived the week.

Cormann and followers proved crucial in Friday's spill

Once Cormann absconded to the Dutton camp, Michaelia Cash followed, locking in two others from WA: Ian Goodenough and Slade Brockman.

These were four votes that proved critical in the spill motion on Friday, which was carried narrowly 45-40.

The pressure was so great that at least two Liberals who did not want change had reluctantly signed the petition to ensure it would get the 43 signatures demanded by Turnbull.

Warren Entsch and Karen Andrews signed, but then voted against the leadership spill motion on Friday — that is, they provided the necessary support for the partyroom to have an emergency meeting but then voted to stick with Turnbull.

One senior Turnbull backer, echoing a widespread view inside the party room, says Turnbull's leadership was cooked as soon as 35 Liberals voted for Peter Dutton in the surprise ballot brought on by the PM last Tuesday.

According to colleagues, Cormann is either the man who was instrumental in Turnbull's destruction or courageous enough to end the damage early.

He is obviously hurting, having played such a key role in bringing down a PM. Some say he is a diminished figure.

Others are adamant he acted appropriately give the awful circumstance.

"In time, people will realise that Mathias did the right thing," one Cabinet minister says.

"The party needed a circuit-breaker and no-one else was prepared to do it.

"He did what he thought was in the best interests of the partyroom. If it hadn't ended for Malcolm on Friday, it would have ended in a fortnight's time."